Initiator composition for curing resin

ABSTRACT

An initiator composition, including at least two compounds represented by the chemical formula R—CO—O—O—CO—R and a compound represented by R 1 —O—O—R 2 , where R represents a C 2 -C 12  alkyl or a C 6 -C 10  aryl or substituted aryl, and R 1  and R 2  independently, at each occurrence, represent a C 1 -C 10  alkyl or a C 6 -C 10  aryl.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of International PatentApplication No. PCT/CN2013/074225 with an international filing date ofApr. 16, 2013, designating the United States, now pending, and furtherclaims priority benefits to Chinese Patent Application No.201210116111.X filed Apr. 19, 2012. The contents of all of theaforementioned applications, including any intervening amendmentsthereto, are incorporated herein by reference. Inquiries from the publicto applicants or assignees concerning this document or the relatedapplications should be directed to: Matthias Scholl P.C., Attn.: Dr.Matthias Scholl Esq., 245 First Street, 18th Floor, Cambridge, Mass.02142.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an initiator composition.

2. Description of the Related Art

A typical curing system for unsaturated polyester resins at roomtemperature employs a ketone peroxide such as methyl ethyl ketoneperoxide or cyclohexanone peroxide as an initiator, a cobalt salt as anaccelerator, or employs benzoyl peroxide as an initiator, tertiary amineas an accelerator. However, the curing system can only cure unsaturatedpolyester resins at room temperature, if the temperature is no more than15° C., the gel time is very long, the curing speed and the degree ofcure are very low, and the mechanical properties of the cured substancesleave much to be desired.

SUMMARY OF THE INVENTION

In view of the above-described problems, it is one objective of theinvention to provide an initiator composition that can accelerate thecuring speed of unsaturated polyester resins at different temperatureparticularly at temperatures no more than 15° C., and improve themechanical properties of the cured substances.

The curing of unsaturated polyester resins includes three stages:gelation, shaping, and aging. The gelation means the resins transformfrom a viscous flow state to a semisolid gel. The shaping means theresins transform from the semisolid gel to have a certain hardness andfixed shape. The aging means the shaped resins are being hardenednaturally to have stable chemical and physical properties. The aginggenerally last for 3-10 days.

The principle of the curing of unsaturated polyester resins issummarized as follows. An initiator can initiate the chain initiation ofunsaturated polyester resins. The initiator is a compound comprising aweak bond and tends to decompose into free radicals. In the presence ofthermal or radiant energy, the weak bond breaks and the initiatordecomposes to yield two free radicals. The resulting free radicalsattack the unsaturated polyester resins to produce radical monomersthereby accelerating the curing of the resins.

To achieve the above objective, in accordance with one embodiment of theinvention, there is provided an initiator composition comprising: atleast two compounds represented by a formula of R—CO—O—O—CO—R and acompound represented by R₁—O—O—R₂, where R represents a C₂-C₁₂ alkyl ora C₆-C₁₀ aryl or substituted aryl, R₁ and R₂ independently, at eachoccurrence, represents a C₁-C₁₀ alkyl or a C₆-C₁₀ aryl.

In a class of this embodiment, the two compounds represented by theformula of R—CO—O—O—CO—R are a diacyl peroxide selected from the groupconsisting of benzoyl peroxide, 2,4-dichlorobenzene acyl peroxide,lauroyl peroxide, and diacetyl peroxide, and the compound represented byR₁—O—O—R₂ is an alkyl peroxide selected from the group consisting ofdicumyl peroxide, di-t-butyl peroxide, and t-butyl cumyl peroxide.

In a class of this embodiment, the initiator composition comprisesbetween 50 and 95 parts by weight of the two compounds represented bythe formula of R—CO—O—O—CO—R and between 5 and 50 parts by weight of thecompound represented by R₁—O—O—R₂.

In a class of this embodiment, the initiator composition comprisesbetween 75 and 95 parts by weight of the two compounds represented bythe formula of R—CO—O—O—CO—R and between 5 and 25 parts by weight of thecompound represented by R₁—O—O—R₂.

In a class of this embodiment, the initiator composition comprises 75parts by weight of the diacyl peroxide and 25 parts by weight of thealkyl peroxide. Specifically, the diacyl peroxide comprises 25 parts byweight of the benzoyl peroxide, 30 parts by weight of2,4-dichlorobenzene acyl peroxide, and 20 parts by weight of lauroylperoxide, and the alkyl peroxide is di-t-butyl peroxide.

In a class of this embodiment, the initiator composition comprises 95parts by weight of the diacyl peroxide and 5 parts by weight of thealkyl peroxide. Specifically, the diacyl peroxide comprises 35 parts byweight of the benzoyl peroxide, 40 parts by weight of2,4-dichlorobenzene acyl peroxide, 10 parts by weight of lauroylperoxide, and 10 parts by weight of diacetyl peroxide, and the alkylperoxide is t-butyl cumyl peroxide.

In a class of this embodiment, the initiator composition comprises 90parts by weight of the diacyl peroxide and 10 parts by weight of thealkyl peroxide. Specifically, the diacyl peroxide comprises 40 parts byweight of the benzoyl peroxide and 50 parts by weight of2,4-dichlorobenzene acyl peroxide, and the alkyl peroxide is dicumylperoxide.

In a class of this embodiment, the initiator composition furthercomprises a compound represented by a formula of R₁—CO—O—O—R₂, where R₁represents a C₁-C₁₀ alkyl or a C₆-C₁₀ aryl, R₂ represents a C₁-C₁₀alkyl, the compound represented by the formula of R₁—CO—O—O—R₂ is acarboxylic ester peroxide selected from the group consisting oftert-butyl peroxybenzoate (TBPB), tert-Butyl peroxy diethyl acetate,t-butyl peroctoate (TBPO), and the initiator composition comprisesbetween 70 and 85 parts by weight of the two compounds represented bythe formula of R—CO—O—O—CO—R, between 5 and 15 parts by weight of thecompound represented by R₁—O—O—R₂, and between 5 and 15 parts by weightof the compound represented by a formula of R₁—CO—O—O—R₂.

In a class of this embodiment, the diacyl peroxide is 75 parts byweight, the alkyl peroxide is 12 parts by weight, and the carboxylicester peroxide is 13 parts by weight, the diacyl peroxide comprises 35parts by weight of benzoyl peroxide and 40 parts by weight of2,4-dichlorobenzene acyl peroxide, the alkyl peroxide is dicumylperoxide, and the carboxylic ester peroxide is tert-butylperoxybenzoate.

Advantages according to embodiments of the invention are summarized asfollows: the initiator composition can accelerate the curing speed ofunsaturated polyester resins at different temperature particularly attemperatures no more than 15° C., and improve the mechanical propertiesof the cured substances.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described hereinbelow with reference to accompanyingdrawings, in which:

FIG. 1 is a curve chart of a gel time of unsaturated polyester resinsinitiated by an initiator composition of the invention at differenttemperatures;

FIG. 2 is a local enlarged view of FIG. 1;

FIG. 3 is a curve chart of a curing time of unsaturated polyester resinsinitiated by an initiator composition of the invention at differenttemperatures; and

FIG. 4 is a local enlarged view of FIG. 3.

DETAILED DESCRIPTION OF THE EMBODIMENTS

For further illustrating the invention, experiments detailing aninitiator composition are described below. It should be noted that thefollowing examples are intended to describe and not to limit theinvention.

Experiments show that diacyl peroxides comprising benzoyl peroxide,2,4-dichlorobenzene acyl peroxide, lauroyl peroxide, and diacetylperoxide have a short half time and low critical temperature, which canshorten the gel time of unsaturated polyester resins.

The alkyl peroxides comprising dicumyl peroxide, di-t-butyl peroxide,t-butyl cumyl peroxide have a high critical temperature, which canshorten the shaping time (also called the post curing time) ofunsaturated polyester resins.

The carboxylic ester peroxides comprising tert-butyl peroxybenzoate(TBPB), tert-Butyl peroxy diethyl acetate, t-butyl peroctoate (TBPO)have a high critical temperature, which can shorten the curing time(which is a total of the gel time and the post curing time) ofunsaturated polyester resins.

The unsaturated polyester resins involved in this invention are formedby the polycondensation of unsaturated dicarboxylic acids (anhydrides),saturated dicarboxylic acids (anhydrides), and diols or polyols. Afterthe polycondensation, a diluent such as styrene, an inhibitor, and anaccelerator are added to the resins, thereby producing a liquidpre-accelerated unsaturated polyester resin (the product can bepurchased from the market).

The pre-accelerated unsaturated polyester resin is selected from thegroup consisting of phthalandione type unsaturated polyester resin,isophthalic unsaturated polyester resin, bisphenol A-type unsaturatedpolyester resin, dicyclopentadiene unsaturated polyester resin,hexachloro-endo-methylenetetrahydrophthalic acid-based unsaturatedpolyester acetate resin, vinyl ester resin, and allyl resin.

The pre-accelerated unsaturated polyester resin is mainly applied to butis not limited to artificial marble, artificial agate, putty, cement,bonding agent, and concrete, with a number-average molecular weight of1000-10000, preferably, 1000-6000, and more preferably, 1000-3000.

The inhibitor is selected from the group consisting of hydroquinone,2,5-di-tert-butyl hydroquinone, methyl hydroquinone, p-benzoquinone,4-tert-butylcatechol, the accelerator is selected from the groupconsisting of N, N-dimethyl aniline, N, N-diethylaniline, N,N-dimethyl-p-toluidine, N-methyl —N-hydroxyethyl aniline,N-methyl-N-hydroxyethyl p-toluidine, N- methyl —N-hydroxypropylp-toluidine, N, N-dihydroxyethyl aniline, and a homologue thereof.

The curing process of the invention is summarized as follows. 0.3-3.0parts by weight of the initiator composition of the invention are addedto 100 parts by weight of the pre-accelerated unsaturated polyesterresin and mixed. In contrast to conventional initiators, the initiatorcomposition can accelerate the curing speed of unsaturated polyesterresins at different temperature particularly at temperatures no morethan 15° C., and improve the mechanical properties of the curedsubstances.

The initiator composition comprises at least two compounds representedby a formula of R—CO—O—O—CO—R and a compound represented by R₁—O—O—R₂,where R represents a C₂-C₁₂ alkyl or a C₆-C₁₀ aryl or substituted aryl,R₁ and R₂ independently, at each occurrence, represents a C₁-C₁₀ alkylor a C₆-C₁₀ aryl.

The two compounds represented by the formula of R—CO—O—O—CO—R are adiacyl peroxide selected from the group consisting of benzoyl peroxide,2,4-dichlorobenzene acyl peroxide, lauroyl peroxide, and diacetylperoxide, and the compound represented by R₁—O—O—R₂ is an alkyl peroxideselected from the group consisting of dicumyl peroxide, di-t-butylperoxide, and t-butyl cumyl peroxide.

The initiator composition comprises between 50 and 95 parts by weight ofthe two compounds represented by the formula of R—CO—O—O—CO—R andbetween 5 and 50 parts by weight of the compound represented byR₁—CO—O—O—R₂.

The initiator composition comprises between 75 and 95 parts by weight ofthe two compounds represented by the formula of R—CO—O—O—CO—R andbetween 5 and 25 parts by weight of the compound represented byR₁—CO—O—O—R₂.

Specifically, the initiator composition comprises 75 parts by weight ofthe diacyl peroxide and 25 parts by weight of the alkyl peroxide.Specifically, the diacyl peroxide comprises 25 parts by weight of thebenzoyl peroxide, 30 parts by weight of 2,4-dichlorobenzene acylperoxide, and 20 parts by weight of lauroyl peroxide, and the alkylperoxide is di-t-butyl peroxide.

The initiator composition comprises 95 parts by weight of the diacylperoxide and 5 parts by weight of the alkyl peroxide. Specifically, thediacyl peroxide comprises 35 parts by weight of the benzoyl peroxide, 40parts by weight of 2,4-dichlorobenzene acyl peroxide, 10 parts by weightof lauroyl peroxide, and 10 parts by weight of diacetyl peroxide, andthe alkyl peroxide is t-butyl cumyl peroxide.

The initiator composition comprises 90 parts by weight of the diacylperoxide and 10 parts by weight of the alkyl peroxide. Specifically, thediacyl peroxide comprises 40 parts by weight of the benzoyl peroxide and50 parts by weight of 2,4-dichlorobenzene acyl peroxide, and the alkylperoxide is dicumyl peroxide.

The initiator composition further comprises a compound represented by aformula of R₁—CO—O—O—R₂, where R₁ represents a C₁-C₁₀ alkyl or a C₆-C₁₀aryl, R₂ represents a C₁-C₁₀ alkyl.

The compound represented by the formula of R₁—CO—O—O—R₂ is a carboxylicester peroxide selected from the group consisting of tert-butylperoxybenzoate (TBPB), tert-Butyl peroxy diethyl acetate, t-butylperoctoate (TBPO).

The initiator composition comprises between 70 and 85 parts by weight ofthe two compounds represented by the formula of R—CO—O—O—CO—R, between 5and 15 parts by weight of the compound represented by R₁—O—O—R₂, andbetween 5 and 15 parts by weight of the compound represented by aformula of R₁—CO—O—O—R₂.

The diacyl peroxide is 75 parts by weight, the alkyl peroxide is 12parts by weight, and the carboxylic ester peroxide is 13 parts byweight, the diacyl peroxide comprises 35 parts by weight of benzoylperoxide and 40 parts by weight of 2,4-dichlorobenzene acyl peroxide,the alkyl peroxide is dicumyl peroxide, and the carboxylic esterperoxide is tert-butyl peroxybenzoate.

The initiator composition is used for the curing of unsaturatedpolyester resins. The unsaturated polyester resins are selected from thegroup consisting of phthalandione type unsaturated polyester resin,isophthalic unsaturated polyester resin, bisphenol A-type unsaturatedpolyester resin, dicyclopentadiene unsaturated polyester resin,hexachloro-endo-methylenetetrahydrophthalic acid-based unsaturatedpolyester acetate resin, vinyl ester resin, and allyl resin.

The following are some examples for the initiator composition of theinvention.

Initiator composition No. 1 (by weight), total weight is 100 parts:

-   -   benzoyl peroxide: 40 parts by weight;    -   2,4-dichlorobenzene acyl peroxide: 50 parts by weight;    -   dicumyl peroxide: 10 parts by weight.

Initiator composition No. 2 (by weight), total weight is 100 parts:

-   -   benzoyl peroxide: 35 parts by weight;    -   2,4-dichlorobenzene acyl peroxide: 40 parts by weight;    -   lauroyl peroxide: 10 parts by weight;    -   diacetyl peroxide : 10 parts by weight;    -   t-butyl cumyl peroxide: 5 parts by weight.

Initiator composition No. 3 (by weight), total weight is 100 parts:

-   -   benzoyl peroxide: 25 parts by weight;    -   2,4-dichlorobenzene acyl peroxide: 30 parts by weight;    -   lauroyl peroxide: 20 parts by weight;    -   di-t-butyl peroxide: 25 parts by weight.

Initiator composition No. 4 (by weight), total weight is 100 parts:

-   -   benzoyl peroxide: 25 parts by weight;    -   lauroyl peroxide: 25 parts by weight;    -   t-butyl cumyl peroxide: 50 parts by weight.

Initiator composition No. 5 (by weight), total weight is 100 parts:

-   -   benzoyl peroxide: 35 parts by weight;    -   2,4-dichlorobenzene acyl peroxide: 40 parts by weight;    -   tert-butyl peroxybenzoate: 13 parts by weight;    -   dicumyl peroxide: 12 parts by weight.

Initiator composition No. 6 (by weight), total weight is 100 parts:

-   -   benzoyl peroxide: 30 parts by weight;    -   diacetyl peroxide : 30 parts by weight;    -   lauroyl peroxide: 20 parts by weight;    -   tert-butyl peroxybenzoate: 5 parts by weight;    -   tert-butyl peroxy diethyl acetate: 10 parts by weight;    -   di-t-butyl peroxide: 5 parts by weight.

Initiator composition No. 7 (by weight), total weight is 100 parts:

-   -   benzoyl peroxide: 35 parts by weight;    -   lauroyl peroxide: 40 parts by weight;    -   tert-butyl peroxybenzoate: 10 parts by weight;    -   di-t-butyl peroxide: 6 parts by weight;    -   dicumyl peroxide: 9 parts by weight.

Initiator composition No. 8 (by weight), total weight is 100 parts:

-   -   benzoyl peroxide: 25 parts by weight;    -   diacetyl peroxide: 20 parts by weight;    -   lauroyl peroxide: 30 parts by weight;    -   2,4-dichlorobenzene acyl peroxide: 10 parts by weight;    -   tert-butyl peroxybenzoate: 5 parts by weight;    -   di-t-butyl peroxide: 10 parts by weight.

Initiator composition No. 9 (by weight), total weight is 100 parts:

-   -   benzoyl peroxide: 30 parts by weight;    -   2,4-dichlorobenzene acyl peroxide: 40 parts by weight;    -   tert-butyl peroxybenzoate: 5 parts by weight;    -   tert-butyl peroxy diethyl acetate: 10 parts by weight;    -   t-butyl peroctoate 10 parts by weight;    -   di-t-butyl peroxide: 5 parts by weight.

Initiator composition No. 10 (by weight), total weight is 100 parts:

-   -   benzoyl peroxide: 40 parts by weight;    -   diacetyl peroxide: 35 parts by weight;    -   tert-butyl peroxybenzoate: 10 parts by weight;    -   di-t-butyl peroxide: 5 parts by weight;    -   dicumyl peroxide: 5 parts by weight;    -   t-butyl cumyl peroxide 5 parts by weight.

Example 1

At 0° C., 5° C., 10° C., 15° C., and 20° C., 100 g of dicyclopentadieneunsaturated polyester resin No. 946 from Jiangsu Yabang Coating Co.,Ltd., 0.032 g of p-benzoquinone (technical grade), and 0.52 g of N,N-dimethyl p-toluidine (technical grade) were uniformly mixed.Thereafter, 1.5 g of the initiator composition No. 1 was added to themixture, and the gel time and the curing time of the mixture weremeasured according to Chinese National Standard GB/T 7193-2008. Theresults are listed in Table 1.

The cured resin having a temperature of 5° C. was allowed to stand at 5°C. for 96 hours (this is an aging stage). Thereafter, the Barcolhardness of the cured resin was measured using a Barcol hardmeter(Beijing ShidaishanfengTechnology Co., HBA-1) according to ChineseNational Standard GB/T 3854-2005, the bending strength of the curedresin was measured using a computer-controlled electronic universaltesting machine (Shenzhen Reger Instrument Co.,Ltd, RGM-100) accordingto Chinese National Standard GB/T 2570-1995, and the impact strength ofthe cured resin was measured using an electronic combination-type impacttesting machine (Chengde Jingmi Precision Testing Machine Co., Ltd.,XJC-25D) according to Chinese National Standard GB/T 2571-1995. Theresults are listed in Table 2.

Example 2

The experimental conditions and operations are the same as that inExample 1 except that the initiator composition No. 2 is substituted forthe initiator composition No. 1. The gel time and curing time atdifferent temperatures are listed in Table 1, and the Barcol hardness,the bending strength, and the impact strength of the cured resin at 5°C. are listed in Table 2.

Example 3

The experimental conditions and operations are the same as that inExample 1 except that the initiator composition No. 3 is substituted forthe initiator composition No. 1. The gel time and curing time atdifferent temperatures are listed in Table 1, and the Barcol hardness,the bending strength, and the impact strength of the cured resin at 5°C. are listed in Table 2.

Example 4

The experimental conditions and operations are the same as that inExample 1 except that the initiator composition No. 4 is substituted forthe initiator composition No. 1. The gel time and curing time atdifferent temperatures are listed in Table 1, and the Barcol hardness,the bending strength, and the impact strength of the cured resin at 5°C. are listed in Table 2.

Example 5

The experimental conditions and operations are the same as that inExample 1 except that the initiator composition No. 5 is substituted forthe initiator composition No. 1. The gel time and curing time atdifferent temperatures are listed in Table 1, and the Barcol hardness,the bending strength, and the impact strength of the cured resin at 5°C. are listed in Table 2.

Example 6

The experimental conditions and operations are the same as that inExample 1 except that the initiator composition No. 6 is substituted forthe initiator composition No. 1. The gel time and curing time atdifferent temperatures are listed in Table 1, and the Barcol hardness,the bending strength, and the impact strength of the cured resin at 5°C. are listed in Table 2.

Example 7

The experimental conditions and operations are the same as that inExample 1 except that the initiator composition No. 7 is substituted forthe initiator composition No. 1. The gel time and curing time atdifferent temperatures are listed in Table 1, and the Barcol hardness,the bending strength, and the impact strength of the cured resin at 5°C. are listed in Table 2.

Example 8

The experimental conditions and operations are the same as that inExample 1 except that the initiator composition No. 8 is substituted forthe initiator composition No. 1. The gel time and curing time atdifferent temperatures are listed in Table 1, and the

Barcol hardness, the bending strength, and the impact strength of thecured resin at 5° C. are listed in Table 2.

Example 9

The experimental conditions and operations are the same as that inExample 1 except that the initiator composition No. 9 is substituted forthe initiator composition No. 1. The gel time and curing time atdifferent temperatures are listed in Table 1, and the Barcol hardness,the bending strength, and the impact strength of the cured resin at 5°C. are listed in Table 2.

Example 10

The experimental conditions and operations are the same as that inExample 1 except that the initiator composition No. 10 is substitutedfor the initiator composition No. 1. The gel time and curing time atdifferent temperatures are listed in Table 1, and the Barcol hardness,the bending strength, and the impact strength of the cured resin at 5°C. are listed in Table 2.

Comparative example 1

The experimental conditions and operations are the same as that inExample 1 except that benzoperoxide (technical grade) is substituted forthe initiator composition No. 1. The gel time and curing time atdifferent temperatures are listed in Table 1, and the Barcol hardness,the bending strength, and the impact strength of the cured resin at 5°C. are listed in Table 2.

TABLE 1 Gel time and curing time at different temperatures Exam- Exam-Exam- Exam- Example Comparative Temperature Items ple 1 ple 2 ple 3 ple4 Example 5 Example 6 Example 7 Example 8 Example 9 10 example 1 0° C.Gel time  4′  4′  4′  5′  5′  6′  7′  7′  9′  8′ 30′ 10″ 38″ 56″ 50″ 40″26″ 52″ 12″ 17″ 24″ 40″ Curing 20′ 21′ 22′ 22′ 10′ 11′ 12′ 12′ 13′ 13′time 18″ 44″ 19″ 57″ 45″ 32″ 33″ 13″ 20″ 00″ Not cured 5° C. Gel time 2′  2′  3′  4′  3′  4′  5′  5′  7′  6′ 15′ 26″ 55″ 14″ 00″ 51″ 41″ 50″22″ 01″ 19″ 42″ Curing 14′ 16′ 16′ 17′  7′  8′  9′  8′ 10′ 10′ 38′ time51″ 23″ 42″ 47″ 25″ 13″ 33″ 54″ 42″ 21″ 10″ 10° C. Gel time  1′  2′  2′ 2′  2′  3′  4′  3′  5′  4′ 10′ 39″ 03″ 16″ 37″ 30″ 10″ 25″ 54″ 16″ 56″38″ Curing 10′ 12′ 12′ 13′  5′  5′  7′  6′  8′  7′ 23′ time 59″ 21″ 41″21 00″ 50″ 08″ 26″ 20″ 55″ 30″ 15° C. Gel time  1′  1′  1′  1′  1′  2′ 3′  2′  4′  3′  6′ 01″ 24″ 37″ 54″ 49″ 21″ 21″ 52″ 07″ 44″ 20″ Curing 7′  8′  9′  9′  3′  4′  5′  4′  6′  5′ 12′ time 55″ 43″ 05″ 51″ 19″ 02″11″ 33″ 13″ 53″ 33″ 20° C. Gel time 51″ 55″  1′  1′  1′  1′  2′  2′  3′ 3′  4′ 10″ 25″ 21″ 56″ 43″ 25″ 22″ 03″ 25″ Curing  5′  6′  6′  6′  2′ 2′  3′  3′  4′  4′  7′ time 40″ 03″ 20″ 38″ 31″ 59″ 55″ 20″ 30″ 18″ 47″

TABLE 2 Barcol hardness, bending strength, and impact strength of curedresin at 5° C. Example Comparative Items Example 1 Example 2 Example 3Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 10 example 1Barcol 49 47 48 45 49 47 45 48 46 47 32 hardness Bending 126 122 125 118125 120 123 122 116 118 97 strength (MPa) Impact strength 2.8 2.9 2.82.5 2.7 2.6 2.7 2.6 2.8 2.8 1.8 (kJ/m²)

The gel time is calculated from the stirring to the occurrence of gel.The curing time is calculated from the stirring to the formation of acured resin having certain hardness, which is total of the gel time andthe shaping time.

Data in Table 1 correspond to FIGS. 1-4.

As shown in FIGS. 1-2, the initiator compositions in Examples 1-10 cansignificantly shorten the gel time of unsaturated polyester resins atlow and normal temperatures.

As shown in FIGS. 3-4, the initiator compositions in Examples 1-10 cansignificantly shorten the curing time of unsaturated polyester resins atlow and normal temperatures.

As shown in FIGS. 1 and 3, in Examples 1-4 and the comparative example1, the gel time is significantly shortened, but the curing time is long,which does not benefit the construction; in Examples 5-10 and thecomparative example 1, both the gel time and the curing time aresignificantly shortened, which is beneficial to the construction.

Data in Table 2 show that the initiator composition can significantlyimprove the degree of cure of unsaturated polyester resins at lowtemperatures, and improve the mechanical properties of cured resins.

While particular embodiments of the invention have been shown anddescribed, it will be obvious to those skilled in the art that changesand modifications may be made without departing from the invention inits broader aspects, and therefore, the aim in the appended claims is tocover all such changes and modifications as fall within the true spiritand scope of the invention.

The invention claimed is:
 1. An initiator composition, comprising: atleast two compounds represented by a formula of R—CO—O—O—CO—R and acompound represented by R₁—O—O—R₂, wherein R represents a C₂-C₁₂ alkylor a C₆-C₁₀ aryl or substituted aryl, R₁ and R₂ independently, at eachoccurrence, represents a C₁-C₁₀ alkyl or a C₆-C₁₀ aryl.
 2. The initiatorcomposition of claim 1, wherein the two compounds represented by theformula of R—CO—O—O—CO—R are a diacyl peroxide selected from the groupconsisting of benzoyl peroxide, 2,4-dichlorobenzene acyl peroxide,lauroyl peroxide, and diacetyl peroxide, and the compound represented byR₁—O—O—R₂ is an alkyl peroxide selected from the group consisting ofdicumyl peroxide, di-t-butyl peroxide, and t-butyl cumyl peroxide. 3.The initiator composition of claim 2, comprising between 50 and 95 partsby weight of the two compounds represented by the formula ofR—CO—O—O—CO—R and between 5 and 50 parts by weight of the compoundrepresented by R₁—O—O—R₂.
 4. The initiator composition of claim 3,comprising between 75 and 95 parts by weight of the two compoundsrepresented by the formula of R—CO—O—O—CO—R and between 5 and 25 partsby weight of the compound represented by R₁—O—O—R₂.
 5. The initiatorcomposition of claim 4, comprising 75 parts by weight of the diacylperoxide and 25 parts by weight of the alkyl peroxide, wherein thediacyl peroxide comprises 25 parts by weight of the benzoyl peroxide, 30parts by weight of 2,4-dichlorobenzene acyl peroxide, and 20 parts byweight of lauroyl peroxide, and the alkyl peroxide is di-t-butylperoxide.
 6. The initiator composition of claim 4, comprising 95 partsby weight of the diacyl peroxide and 5 parts by weight of the alkylperoxide, wherein the diacyl peroxide comprises 35 parts by weight ofthe benzoyl peroxide, 40 parts by weight of 2,4-dichlorobenzene acylperoxide, 10 parts by weight of lauroyl peroxide, and 10 parts by weightof diacetyl peroxide, and the alkyl peroxide is t-butyl cumyl peroxide.7. The initiator composition of claim 4, comprising 90 parts by weightof the diacyl peroxide and 10 parts by weight of the alkyl peroxide,wherein the diacyl peroxide comprises 40 parts by weight of the benzoylperoxide and 50 parts by weight of 2,4-dichlorobenzene acyl peroxide,and the alkyl peroxide is dicumyl peroxide.
 8. The initiator compositionof claim 1, further comprising a compound represented by a formula ofR₁—CO—O—O—R₂, wherein R₁ represents a C₁-C₁₀ alkyl or a C₆-C₁₀ aryl, R₂represents a C₁-C₁₀ alkyl, the compound represented by the formula ofR₁—CO—O—O—R₂ is a carboxylic ester peroxide selected from the groupconsisting of tert-butyl peroxybenzoate (TBPB), tert-butyl peroxydiethyl acetate, t-butyl peroctoate (TBPO), and the initiatorcomposition comprises between 70 and 85 parts by weight of the twocompounds represented by the formula of R—CO—O—O—CO—R, between 5 and 15parts by weight of the compound represented by R₁—O—O—R₂, and between 5and 15 parts by weight of the compound represented by a formula ofR₁—CO—O—O—R₂.
 9. The initiator composition of claim 8, wherein thediacyl peroxide is 75 parts by weight, the alkyl peroxide is 12 parts byweight, and the carboxylic ester peroxide is 13 parts by weight, thediacyl peroxide comprises 35 parts by weight of benzoyl peroxide and 40parts by weight of 2,4-dichlorobenzene acyl peroxide, the alkyl peroxideis dicumyl peroxide, and the carboxylic ester peroxide is tert-butylperoxybenzoate.
 10. The initiator composition of claim 2, furthercomprising a compound represented by a formula of R₁—CO—O—O—R₂, whereinR₁ represents a C₁-C₁₀ alkyl or a C₆-C₁₀ aryl, R₂ represents a C₁-C₁₀alkyl, the compound represented by the formula of R₁—CO—O—O—R₂ is acarboxylic ester peroxide selected from the group consisting oftert-butyl peroxybenzoate (TBPB), tert-butyl peroxy diethyl acetate,t-butyl peroctoate (TBPO), and the initiator composition comprisesbetween 70 and 85 parts by weight of the two compounds represented bythe formula of R—CO—O—O—CO—R, between 5 and 15 parts by weight of thecompound represented by R₁—O—O—R₂, and between 5 and 15 parts by weightof the compound represented by a formula of R₁—CO—O—O—R₂.
 11. Theinitiator composition of claim 10, wherein the diacyl peroxide is 75parts by weight, the alkyl peroxide is 12 parts by weight, and thecarboxylic ester peroxide is 13 parts by weight, the diacyl peroxidecomprises 35 parts by weight of benzoyl peroxide and 40 parts by weightof 2,4-dichlorobenzene acyl peroxide, the alkyl peroxide is dicumylperoxide, and the carboxylic ester peroxide is tert-butylperoxybenzoate.